Flu season is in full swing in Utah and nationally.
The number of Utahns reporting flu-like illnesses to the state's sentinel clinics has already surpassed tallies at the same point in time during the past couple of years. But it's still nowhere near the peak of the H1N1 flu year of 2008-2009.
"Nobody knows why flu does what it does," said Valoree Vernon, epidemiologist with the Utah Department of Health. "But it's circulating quite a bit, causing a lot of visits to clinics and hospitals."
Flu activity is considered "high" in the state, though there are regions with low to moderate activity, including Summit, Tooele, Wasatch, Weber and Morgan counties.
In the past, flu-like symptoms haven't been reported to this extent until the end of February, said Vernon.
The story is the same nationally, where most of the country is experiencing high levels of flu-like illness, according to the Centers for Disease Control and Prevention.
In Utah, 233 people have been hospitalized, with 56 last week. Children under age 4 and adults 65 years and older have the highest rates of hospitalization.
Last year, considered a mild flu season, cases peaked in March, and 362 people were hospitalized. If the flu continues to spread as it has, this year could shape up to be worse.
While the health department is not "alarmed" at the number of illnesses reported so far in an average year, 500 to 600 people are hospitalized it is on alert because the flu appears to be spreading rapidly. The state lab has had to limit the number of samples it is testing for the flu because of the demand, Vernon said.
For example, it tested nearly 100 cases last week. Instead of testing all samples, it is only testing ones for hospitalized patients.
The strain circulating is type A (H3), which Vernon said is covered by the vaccine. "It's still not too late to get vaccinated," she said. "The vaccine is a very good match for what's circulating right now."
Among those hospitalized, the vaccination status of about 60 percent is unknown. Among the others, 19 percent were vaccinated and 22 percent were not.
Nationally, 18 children had died from the flu through Dec. 29, according to the CDC. No Utah children or adults have died, Vernon said.
Emergency physicians have reported they are seeing higher number of patients with flu symptoms nationally. The American College of Emergency Physicians are urging the sick to stay home from school or work.
Typical flu symptoms include fever, sore throat, runny nose, headache, fatigue and muscle or body aches. Adults should seek emergency care if they struggle to breathe, feel pain or pressure in the chest or abdomen, have sudden dizziness, confusion or severe or persistent vomiting, according to the ER doctors' group.
It says children should be seen right away if they have those symptoms or have bluish skin color, aren't waking up or interacting, or are so irritable they don't want to be held.